Financial Highlights - Financial Highlights for Limited Partner Class (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class A [Member]
Per Redeemable Unit Performance (for a unit outstanding throughout the year):
Net asset value per Redeemable Unit, beginning of period/year	$ 1,265.64	$ 1,335.70
Net asset value per Redeemable Unit, end of period/year	1,300.66	1,265.64	$ 1,335.70
Class D [Member]
Per Redeemable Unit Performance (for a unit outstanding throughout the year):
Net asset value per Redeemable Unit, end of period/year	1,010.75
Limited Partners [Member] | Class A [Member]
Per Redeemable Unit Performance (for a unit outstanding throughout the year):
Net realized and unrealized gains (losses)	115.36	(1.95)	152.57
Net investment loss	(80.34)	(68.11)	(85.25)
Increase (decrease) for the period/year	35.02	(70.06)	67.32
Net asset value per Redeemable Unit, beginning of period/year	1,265.64	1,335.70	1,268.38
Net asset value per Redeemable Unit, end of period/year	$ 1,300.66	$ 1,265.64	$ 1,335.70
Ratios to Average Limited Partners' Capital:
Net investment loss	(6.40%)	(5.40%)	(6.50%)
Operating expenses	6.50%	6.20%	6.70%
Incentive fees	1.60%
Total expenses	8.10%	6.20%	6.70%
Total return:
Total return before incentive fees	4.40%	(5.20%)	5.30%
Incentive fees	(1.60%)
Total return after incentive fees	2.80%	(5.20%)	5.30%
Limited Partners [Member] | Class D [Member]
Per Redeemable Unit Performance (for a unit outstanding throughout the year):
Net realized and unrealized gains (losses)	$ 36.19
Net investment loss	(25.44)
Increase (decrease) for the period/year	10.75
Net asset value per Redeemable Unit, beginning of period/year	1,000.00
Net asset value per Redeemable Unit, end of period/year	$ 1,010.75	$ 1,000.00
Ratios to Average Limited Partners' Capital:
Net investment loss	(4.10%)
Operating expenses	5.10%
Incentive fees	1.00%
Total expenses	6.10%
Total return:
Total return before incentive fees	2.10%
Incentive fees	(1.00%)
Total return after incentive fees	1.10%